1. Field of the Invention
The present invention relates to a seatbelt reminder system, and, more particularly, to a seatbelt reminder system which changes a reminder method according to a situation.
2. Description of the Related Art
In general, seatbelts in a vehicle are capable of fastening the bodies of crew members to their seats. Accordingly, a seatbelt reminder system is used to avoid the unfastened state of each seatbelt as much as possible.
The system employs different reminder schemes, such as a visual warning to visually notify the unfastened state of the seatbelt to a crew member by means of, for example, lighting of an indicator, and an acoustic warning to give acoustic notification to the crew member by giving a buzzer sound.
The technique of the system is described in, for example, U.S. Pat. No. 6,278,358.
The system is activated upon separately detecting the fastening state of a seatbelt (hereinafter referred to as “seat-belt fastening state” whenever convenient) and the running state of the vehicle, and warns crew members. This technique can cope with the unfastened state of the seatbelt after the engine is set running.
The prior art technique does not however distinguish a reminder method in a case where the running state of a vehicle is detected when the unfastened state of a seatbelt is detected from a reminder method in a case where the unfastened state of the seatbelt is detected when the running state of the vehicle is detected.
In the case where the unfastened state of a seatbelt is detected when a vehicle is in the running state, the crew member on that seat is very likely to be aware that the seatbelt is not fastened compared with the case where the running state of a vehicle is detected when a seatbelt is in the unfastened state. A reminder if given in that state would annoy the crew member considerably. In other words, no particular measures against such probable annoyance given to crew members have been taken into consideration in the prior art technology.
The seatbelt reminder system should take definition of re-reminding conditions into consideration in addition to the requirement that a reminder should be generated immediately when a seatbelt is apparently unfastened at the time a vehicle starts running.
That is, if, after completion of one cycle of warning comprised of a first reminder and a second reminder, the second reminder is started again without defining a re-reminding condition when a reminding condition on the running state of the vehicle or the unfastened state of the seatbelt is satisfied again, the reminder becomes tedious, giving rather considerable annoyance to the associated crew member. What is more, defining no re-reminding condition would urge the crew member to take an action of fastening the unfastened seatbelt even during driving at a high speed, which is dangerous.